Yes, this is my theory. I'm not for one minute suggesting they moved the body. I'm asking whether it's possible they were there to ask for help to move it (and failed) or for a different reason.
To my mind it makes zero sense for them to believe it would look good to be seen (?) at a (not so local) fair unless Tia had expressed a desire to go there.
Which she didn't or he would have justified looking around a random venue by saying "Tia saw the poster for the fair so we checked there". Why check the fair? Why? Why when there are so many local kiddie areas to check?
One answer is because THEY wanted to blame the disappearance on the travellers. But that's thin bearing in mind she was supposed to be in central Croydon.
Surely there's another reason. My reason is because SH knew travellers. But that's been poo-pooed.
I agree there is something significant attached to the fair and it's probably not that TS might have gone there on her own on the way back from Croydon.
The problem I have with CS being aware of TS being dead from the start is the timing. Why did they report her missing so quickly with the body still in the loft? TS was due to stay for the whole weekend. But perhaps there was some routine that forced the timescale e.g. TS was expected to call NS every night before bed or something.
It makes more sense to me that SH put the body in the loft and did his clean-up before CS got home. Then things escalated, TS got reported missing, the police and family descended on the house and there was no opportunity to move the body.
It was only when reporters interviewed the fairground staff after SH gave his interview that it became public knowledge they didn't remember SH/CS asking about TS. Now the police may have interviewed the fairground staff early on if the fairground story was told to them at the start. No reason we would know. Therefore, police may have known very early on who their prime suspect(s) was/were. But then, that makes the deficiencies in the Sunday morning 2 hour search even worse.
I guess we will just have to wait for the trial if indeed there is one.